Constructing the Interconnected Charge Transfer Pathways in Sulfur Composite Cathode for All-Solid-State Lithium–Sulfur Batteries

Abstract

All-solid-state lithium−sulfur batteries (ASSLSBs) have advantageous features, such as high energy, low costs, enhanced safety, and no polysulfide dissolution. However, the use of sulfur as an active material in all-solid-state batteries is difficult because of its ionic and electrical insulating properties. Herein, we introduce a flower-shaped composite material consisting of MoS 2 nanoparticles and sulfur, designed to establish interconnected ionic and electrical conduction pathways at the cathode. As a host material, MoS 2 nanoparticles with a large specific surface area can coconduct Li ions and electrons, possessing the potential for effectively utilizing sulfur. However, MoS 2 nanoparticles are prone to physical-electrochemical isolation by being surrounded by sulfur due to their crumpling property in the process of mixing and impregnation with sulfur. This problem is addressed by mildly milling the MoS 2 nanoparticles and sulfur, after which melt diffusion is applied to generate uniform MoS 2 /sulfur composite materials to establish an interconnected conducting pathway within the composite. A sulfide solid electrolyte (Li 6 PS 5 Cl)-based ASSLSB incorporating the proposed MoS 2 /sulfur composite demonstrates a stable operation over 1000 cycles with a Coulombic efficiency of nearly 100%. This study emphasizes the significance of the structural design of the sulfur composite material on top of the intrinsic properties of the material for high-performance ASSLSBs.